1. Field of the Invention
The present invention relates to dry erasable boards. More particularly, the invention relates to coatings for erasable, markable surfaces for use with erasable marking pens.
2. Description of the Related Art
In the past, traditional classroom education relied entirely upon a "blackboard" and chalk as the medium for demonstrational instruction. This technique has proven to be relatively messy due to the chalk dust and smaller pieces of broken chalk. Blackboards were also limited in the range of chalk colors they could accept, due to their relatively dark color and the difficulty in completely erasing chalk colors other than white. One solution to this problem is the use of overhead projectors or laptop computers, but these units which provide graphics capability are relatively slow and costly for casual use.
A more economical solution to this problem is the use of dry erasable marking systems, or "dry erase boards", which use erasable marking pens to provide the utility of a blackboard or chalkboard, while eliminating the mess of chalk dust and the difficulty of cleanup of multiple colors. Dry erase boards typically have a smooth, markable, coated writing surface formed by coating a substrate with a lacquer coating which is subsequently cured. Dry erase marking pens are typically felt tip marking instruments containing specially formulated inks which satisfactorily mark these coated writing surfaces, and can be substantially fully erased from these surfaces after the ink has dried. These dry-erase markers leave substantially no mess, and erasure typically requires only minimal manual effort using a conventional dry eraser, cloth, or paper tissue.
Previously developed dry-erase boards include writing surfaces made of coated paper or film, melamine, or ceramic which are adhered to smooth, hard, rigid substrates such as paper board, fiber board, plastic, wood, and the like. Coated paper and film based dry-erase surfaces are relatively inexpensive, however they suffer from a number of disadvantages. The erasable, markable character of these surfaces deteriorates gradually with repeated application and erasure of dry erasable inks. The chemical materials used to mark these surfaces often cause deformation of these surfaces, resulting in the formation of non-removable ghost images after continued use. These surfaces are also known to exhibit poor solvent resistance, and are often incompatible with certain dry erase markers. Ceramic based dry erase surfaces provide good erasability but are relatively expensive.
It would therefore be desirable to produce an inexpensive writable-erasable article which provides good erasability after continued use. The article of the present invention provides a solution to this problem. According to the invention, a substrate is coated with a specially formulated epoxy coating on one side, and an adhesive on another side. Surprisingly, the epoxy coating of the invention provides excellent erasability with substantially no ghosting images. It also exhibits good solvent resistance and is compatible with substantially all dry erase markers. The articles formed according to the invention may then be adhered to a support via an adhesive, and sold inexpensively to consumers in the form of a writable-erasable or "dry-erase" boards in a variety of sizes, depending on specific need.